@article{scruggs_basaiah_adams_quesada-ocampo_2017, title={Genetic Diversity, Fungicide Sensitivity, and Host Resistance to Ceratocystis fimbriata Infecting Sweetpotato in North Carolina}, volume={101}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-11-16-1583-re}, abstractNote={Black rot of sweetpotato, caused by Ceratocystis fimbriata, has recently reemerged as a significant threat to sweetpotato production in North Carolina and other states across the United States. This disease has historically been controlled largely through cultural management strategies and, in some cases, fungicide application. The sudden and destructive reemergence of this disease in 2015 created the need for rapidly evaluating disease control strategies. Genetic diversity of current C. fimbriata isolates infecting sweetpotato in North Carolina was assessed using ITS, TEF, and MAT-2 sequences. All 50 tested isolates were confirmed to be of a single mating type, MAT-2, based on PCR amplification. Alignment of ITS, TEF, and MAT-2 sequences revealed all isolates were identical at each locus. Fourteen common sweetpotato cultivars and advanced breeding lines were screened for black rot resistance using two isolates. None of the cultivars were completely resistant to the disease and most were equally susceptible. ‘Stokes Purple’ and ‘Covington’ were the least susceptible, but significantly (P < 0.05) differed only from ‘Bellevue’, the most susceptible cultivar. Sensitivity of 50 C. fimbriata isolates to difenoconazole, fludioxonil, thiabendazole, dicloran, azoxystrobin, pyraclostrobin, fenamidone, and fluazinam was evaluated in vitro. Difenoconazole, thiabendazole, and fluazinam were most effective in reducing mycelia growth. Postharvest fungicide application on black rot-infected roots provided similar results. Low efficacy of dicloran, as well as a range of EC 50 values among isolates, suggests potential resistance to this commonly applied fungicide. Results obtained in this study provide current and useful information so that improved recommendations can be made to reduce losses in sweetpotato to black rot.}, number={6}, journal={PLANT DISEASE}, author={Scruggs, A. C. and Basaiah, T. and Adams, M. L. and Quesada-Ocampo, L. M.}, year={2017}, month={Jun}, pages={994–1001} }
 @article{wallace_adams_ivors_ojiambo_quesada-ocampo_2014, title={First Report of Pseudoperonospora cubensis Causing Downy Mildew on Momordica balsamina and M. charantia in North Carolina}, volume={98}, ISSN={["1943-7692"]}, url={http://europepmc.org/abstract/med/30699625}, DOI={10.1094/pdis-03-14-0305-pdn}, abstractNote={Momordica balsamina (balsam apple) and M. charantia L. (bitter melon/bitter gourd/balsam pear) commonly grow in the wild in Africa and Asia; bitter melon is also cultivated for food and medicinal purposes in Asia (1). In the United States, these cucurbits grow as weeds or ornamentals. Both species are found in southern states and bitter melon is also found in Pennsylvania and Connecticut (3). Cucurbit downy mildew (CDM), caused by the oomycete Pseudoperonospora cubensis, was observed on bitter melon and balsam apple between August and October of 2013 in six North Carolina sentinel plots belonging to the CDM ipmPIPE program (2). Plots were located at research stations in Johnston, Sampson, Lenoir, Henderson, Rowan, and Haywood counties, and contained six different commercial cucurbit species including cucumbers, melons, and squashes in addition to the Momordica spp. Leaves with symptoms typical of CDM were collected from the Momordica spp. and symptoms varied from irregular chlorotic lesions to circular lesions with chlorotic halos on the adaxial leaf surface. Sporulation on the abaxial side of the leaves was observed and a compound microscope revealed sporangiophores (180 to 200 μm height) bearing lemon-shaped, dark sporangia (20 to 35 × 10 to 20 μm diameter) with papilla on one end. Genomic DNA was extracted from lesions and regions of the NADH dehydrogynase subunit 1 (Nad1), NADH dehydrogynase subunit 5 (Nad5), and internal transcribed spacer (ITS) ribosomal RNA genes were amplified and sequenced (4). BLAST analysis revealed 100% identity to P. cubensis Nad1 (HQ636552.1, HQ636551.1), Nad5 (HQ636556.1), and ITS (HQ636491.1) sequences in GenBank. Sequences from a downy mildew isolate from each Momordica spp. were deposited in GenBank as accession nos. KJ496339 through 44. To further confirm host susceptibility, vein junctions on the abaxial leaf surface of five detached leaves of lab-grown balsam apple and bitter melon were either inoculated with a sporangia suspension (10 μl, 10 4 sporangia/ml) of a P. cubensis isolate from Cucumis sativus (‘Vlaspik' cucumber), or with water as a control. Inoculated leaves were placed in humidity chambers to promote infection and incubated using a 12-h light (21°C) and dark (18°C) cycle. Seven days post inoculation, CDM symptoms and sporulation were observed on inoculated balsam apple and bitter melon leaves. P. cubensis has been reported as a pathogen of both hosts in Iowa (5). To our knowledge, this is the first report of P. cubensis infecting these Momordica spp. in NC in the field. Identifying these Momordica spp. as hosts for P. cubensis is important since these cucurbits may serve as a source of CDM inoculum and potentially an overwintering mechanism for P. cubensis. Further research is needed to establish the role of non-commercial cucurbits in the yearly CDM epidemic, which will aid the efforts of the CDM ipmPIPE to predict disease outbreaks. References: (1) L. K. Bharathi and K. J. John. Momordica Genus in Asia-An Overview. Springer, New Delhi, India, 2013. (2) P. S. Ojiambo et al. Plant Health Prog. doi:10.1094/PHP-2011-0411-01-RV, 2011. (3) PLANTS Database. Natural Resources Conservation Service, USDA. Retrieved from http://plants.usda.gov/ , 7 February 2014. (4) L. M. Quesada-Ocampo et al. Plant Dis. 96:1459, 2012. (5) USDA. Index of Plant Disease in the United States. Agricultural Handbook 165, 1960.}, number={9}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Wallace, E. and Adams, M. and Ivors, K. and Ojiambo, P. S. and Quesada-Ocampo, L. M.}, year={2014}, month={Sep}, pages={1279–1279} }
 @article{kousik_adams_jester_hassell_harrison_holmes_2011, title={Effect of cultural practices and fungicides on Phytophthora fruit rot of watermelon in the Carolinas}, volume={30}, ISSN={["0261-2194"]}, DOI={10.1016/j.cropro.2011.03.012}, abstractNote={Phytophthora fruit rot of watermelon, caused by Phytophthora capsici, is an important and emerging disease in Southeastern U.S.A. The effects of two cultural practices (raised bare ground and raised plastic mulched beds) used for growing watermelon and different fungicide treatments on development of Phytophthora fruit rot were evaluated. The experiments were conducted over three years (2005–2008) at research stations in North Carolina and South Carolina, U.S.A. Fungicides were applied at weekly intervals on the diploid cv. Mickey Lee for an average of five applications. Fruit rot incidence was recorded at the end of each experiment. Fruit rot incidence in the non-treated plots was 66% across two states and six trials. Overall, the levels of fruit rot on the raised bare ground and raised plastic mulched beds were not significantly different. Based on percent disease reduction relative to the non-treated check plots, the fungicide Captan was the most effective across years and locations (range = 23–70%, mean = 57%), followed by mandipropamid (25–65%, mean = 50%), fluopicolide (24–65%, mean = 43%) and cyazofamid (0–48%, mean = 31%). Mefenoxam, the current standard treatment reduced fruit rot by 8–28% (mean = 18%). The addition of copper hydroxide to the spray mix did not significantly enhance effectiveness of Captan or mandipropamid. The variability in fungicide efficacy observed in these experiments across locations and years demonstrates the importance of environmental conditions in disease development and management. Even when the most effective fungicides are used, heavy losses may occur when conditions are highly favorable for disease development. Ultimately, effective control of Phytophthora fruit rot of watermelon will require an integrated management strategy that includes well-drained fields, water management and crop rotation in addition to fungicides.}, number={7}, journal={CROP PROTECTION}, author={Kousik, Chandrasekar S. and Adams, Mike L. and Jester, Wilfred R. and Hassell, Richard and Harrison, Howard F. and Holmes, Gerald J.}, year={2011}, month={Jul}, pages={888–894} }